The present invention relates to a semiconductor memory device, and more particularly to that suitable for application to video field.
Semiconductor memories have been utilized for storing display information for such as information processing system and TV system. Representative semiconductor memories are structured in such that a plurality of memory cells are arranged in a matrix form of rows and columns and one memory cell is selected for read or write for each access cycle. Therefore, an operation speed of such memories and amount of information to be accessed for unit of time have been limited. In order to implement a large amount of data accessing, an interleave technique in which a plurality of memories are alternately accessed and a parallel-serial conversion technique in which a plurality bits of data applied from the outside in series are once held by a register in parallel and data held by the register are stored in a plurality of memories in parallel. According to these technique, effective amount of data accessed for each cycle time is increased remarkably and high speed operation is resultantly achieved.
However, the above two techniques require complicated peripheral control circuits for controlling the respective memories. Therefore, the above two memories systems according to the above two techniques have been fabricated by a large amount of elements, and it has been difficult to fabricate such improved memory system on a semiconductor chip.